I apologize for being insufficiently clear. I request a clear explanation from you, in your own words, first; of the meaning of "affirming the consequent. I expect this be be delivered without a porridge of philosophers’ jargon, and without internet links to other people’s explanations. This should not be too tough. Just pretend that you had to teach the concepts to a class of intelligent students who signed up for your class to learn things which they did not know, and wanted to know. Secondly, I want an explanation of why the principle is not logical, logically flawed, “illicit,” or in some other way unsuitable for mental consumption. Again, please— clearly and in your own words.
sheesh…I don’t have to pander to you any more than I do other people. You are essentially asking me to prove the rules of inference for **modus ponens **and
modus tollens. Rather than bore you, the best way is to give an example. Here’s a demonstration: the first two arguments are valid. The latter two are invalid. You should subsequently see how affirimng the consequent is an illicit inference.
The major premise in each argument involves the truth-function “if–>then,” or what’s called
material implication. This truth-function has semantic rules (which you can see in a truth-table), which is precisely why you can make the former, but not the latter two inferences below.
Modus Ponens:
If it’s snowing outside, then it’s cold.
It’s snowing outside.
Therefore, it’s cold.
Modus Tollens:
If it’s snowing outside, then it’s cold.
Its not cold.
Therefore, it’s not snowing.
Illicitly denying the antecedent:
If it’s snowing outside, then it’s cold.
It’s not snowing outside.
Therefore, it’s not cold.
Illicitly affirming the consequent:
If it’s snowing outside, then it’s cold.
It’s cold.
Therefore, it’s snowing.
All arguments use the same set of facts, but we can see by the logical structure of the arguments that there are two ways of making incorrect inferences from those facts. And the important feature to notice is that the invalidity comes from the logical form of the argument, not those facts themselves. Take the last one: The inference is clearly invalid, since being cold is a not *a sufficient *reason for concluding that it is snowing, though, being cold is a *necessary *condition for it to be snowing outside. So if it is snowing outside, then it is certainly cold. Though being cold doesn’t logically imply it is snowing.
So far, all you’ve offered is a philosophical snow job. Surely, your advanced education suggests that you can accomplish a straightforward explanation.
Don’t ask me to do that again. If you think there is something wrong with these two correct rules of inference above, then the burden of proof is on you to logically demonstrate that error. And I expect to see clearly articulated results, otherwise you’re just trying to pull a philosophical, but nonsensical snowjob.
So far you are way too pretentious for your own good, and you treat these discussions as if they involved a demonstration of intellectual showmanship. But you only have a bachelor’s degree in science, so you might want to stop flying too close to the sun because you’re eventually going to get burned by someone smarter than you. I guarantee it.